package org.mspring.mlog.support.lucene;

import static org.apache.lucene.util.RamUsageEstimator.NUM_BYTES_CHAR;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;

import org.apache.lucene.util.ArrayUtil;

/**
 * 抄袭lucene的英文处理
 * 
 * @author Gao Youbo
 * @since 2013年7月9日
 */
public class PorterStemmer {
    private char[] b;
    private int i, /* offset into b */
    j, k, k0;
    private boolean dirty = false;
    private static final int INITIAL_SIZE = 50;

    public PorterStemmer() {
        b = new char[INITIAL_SIZE];
        i = 0;
    }

    /**
     * reset() resets the stemmer so it can stem another word. If you invoke the
     * stemmer by calling add(char) and then stem(), you must call reset()
     * before starting another word.
     */
    public void reset() {
        i = 0;
        dirty = false;
    }

    /**
     * Add a character to the word being stemmed. When you are finished adding
     * characters, you can call stem(void) to process the word.
     */
    public void add(char ch) {
        if (b.length <= i) {
            b = ArrayUtil.grow(b, i + 1);
        }
        b[i++] = ch;
    }

    /**
     * After a word has been stemmed, it can be retrieved by toString(), or a
     * reference to the internal buffer can be retrieved by getResultBuffer and
     * getResultLength (which is generally more efficient.)
     */
    @Override
    public String toString() {
        return new String(b, 0, i);
    }

    /**
     * Returns the length of the word resulting from the stemming process.
     */
    public int getResultLength() {
        return i;
    }

    /**
     * Returns a reference to a character buffer containing the results of the
     * stemming process. You also need to consult getResultLength() to determine
     * the length of the result.
     */
    public char[] getResultBuffer() {
        return b;
    }

    /* cons(i) is true <=> b[i] is a consonant. */

    private final boolean cons(int i) {
        switch (b[i]) {
        case 'a':
        case 'e':
        case 'i':
        case 'o':
        case 'u':
            return false;
        case 'y':
            return (i == k0) ? true : !cons(i - 1);
        default:
            return true;
        }
    }

    /*
     * m() measures the number of consonant sequences between k0 and j. if c is
     * a consonant sequence and v a vowel sequence, and <..> indicates arbitrary
     * presence,
     * 
     * <c><v> gives 0 <c>vc<v> gives 1 <c>vcvc<v> gives 2 <c>vcvcvc<v> gives 3
     * ....
     */

    private final int m() {
        int n = 0;
        int i = k0;
        while (true) {
            if (i > j)
                return n;
            if (!cons(i))
                break;
            i++;
        }
        i++;
        while (true) {
            while (true) {
                if (i > j)
                    return n;
                if (cons(i))
                    break;
                i++;
            }
            i++;
            n++;
            while (true) {
                if (i > j)
                    return n;
                if (!cons(i))
                    break;
                i++;
            }
            i++;
        }
    }

    /* vowelinstem() is true <=> k0,...j contains a vowel */

    private final boolean vowelinstem() {
        int i;
        for (i = k0; i <= j; i++)
            if (!cons(i))
                return true;
        return false;
    }

    /* doublec(j) is true <=> j,(j-1) contain a double consonant. */

    private final boolean doublec(int j) {
        if (j < k0 + 1)
            return false;
        if (b[j] != b[j - 1])
            return false;
        return cons(j);
    }

    /*
     * cvc(i) is true <=> i-2,i-1,i has the form consonant - vowel - consonant
     * and also if the second c is not w,x or y. this is used when trying to
     * restore an e at the end of a short word. e.g.
     * 
     * cav(e), lov(e), hop(e), crim(e), but snow, box, tray.
     */

    private final boolean cvc(int i) {
        if (i < k0 + 2 || !cons(i) || cons(i - 1) || !cons(i - 2))
            return false;
        else {
            int ch = b[i];
            if (ch == 'w' || ch == 'x' || ch == 'y')
                return false;
        }
        return true;
    }

    private final boolean ends(String s) {
        int l = s.length();
        int o = k - l + 1;
        if (o < k0)
            return false;
        for (int i = 0; i < l; i++)
            if (b[o + i] != s.charAt(i))
                return false;
        j = k - l;
        return true;
    }

    /*
     * setto(s) sets (j+1),...k to the characters in the string s, readjusting
     * k.
     */

    void setto(String s) {
        int l = s.length();
        int o = j + 1;
        for (int i = 0; i < l; i++)
            b[o + i] = s.charAt(i);
        k = j + l;
        dirty = true;
    }

    /* r(s) is used further down. */

    void r(String s) {
        if (m() > 0)
            setto(s);
    }

    /*
     * step1() gets rid of plurals and -ed or -ing. e.g.
     * 
     * caresses -> caress ponies -> poni ties -> ti caress -> caress cats -> cat
     * 
     * feed -> feed agreed -> agree disabled -> disable
     * 
     * matting -> mat mating -> mate meeting -> meet milling -> mill messing ->
     * mess
     * 
     * meetings -> meet
     */

    private final void step1() {
        if (b[k] == 's') {
            if (ends("sses"))
                k -= 2;
            else if (ends("ies"))
                setto("i");
            else if (b[k - 1] != 's')
                k--;
        }
        if (ends("eed")) {
            if (m() > 0)
                k--;
        } else if ((ends("ed") || ends("ing")) && vowelinstem()) {
            k = j;
            if (ends("at"))
                setto("ate");
            else if (ends("bl"))
                setto("ble");
            else if (ends("iz"))
                setto("ize");
            else if (doublec(k)) {
                int ch = b[k--];
                if (ch == 'l' || ch == 's' || ch == 'z')
                    k++;
            } else if (m() == 1 && cvc(k))
                setto("e");
        }
    }

    /* step2() turns terminal y to i when there is another vowel in the stem. */

    private final void step2() {
        if (ends("y") && vowelinstem()) {
            b[k] = 'i';
            dirty = true;
        }
    }

    /*
     * step3() maps double suffices to single ones. so -ization ( = -ize plus
     * -ation) maps to -ize etc. note that the string before the suffix must
     * give m() > 0.
     */

    private final void step3() {
        if (k == k0)
            return; /* For Bug 1 */
        switch (b[k - 1]) {
        case 'a':
            if (ends("ational")) {
                r("ate");
                break;
            }
            if (ends("tional")) {
                r("tion");
                break;
            }
            break;
        case 'c':
            if (ends("enci")) {
                r("ence");
                break;
            }
            if (ends("anci")) {
                r("ance");
                break;
            }
            break;
        case 'e':
            if (ends("izer")) {
                r("ize");
                break;
            }
            break;
        case 'l':
            if (ends("bli")) {
                r("ble");
                break;
            }
            if (ends("alli")) {
                r("al");
                break;
            }
            if (ends("entli")) {
                r("ent");
                break;
            }
            if (ends("eli")) {
                r("e");
                break;
            }
            if (ends("ousli")) {
                r("ous");
                break;
            }
            break;
        case 'o':
            if (ends("ization")) {
                r("ize");
                break;
            }
            if (ends("ation")) {
                r("ate");
                break;
            }
            if (ends("ator")) {
                r("ate");
                break;
            }
            break;
        case 's':
            if (ends("alism")) {
                r("al");
                break;
            }
            if (ends("iveness")) {
                r("ive");
                break;
            }
            if (ends("fulness")) {
                r("ful");
                break;
            }
            if (ends("ousness")) {
                r("ous");
                break;
            }
            break;
        case 't':
            if (ends("aliti")) {
                r("al");
                break;
            }
            if (ends("iviti")) {
                r("ive");
                break;
            }
            if (ends("biliti")) {
                r("ble");
                break;
            }
            break;
        case 'g':
            if (ends("logi")) {
                r("log");
                break;
            }
        }
    }

    /* step4() deals with -ic-, -full, -ness etc. similar strategy to step3. */

    private final void step4() {
        switch (b[k]) {
        case 'e':
            if (ends("icate")) {
                r("ic");
                break;
            }
            if (ends("ative")) {
                r("");
                break;
            }
            if (ends("alize")) {
                r("al");
                break;
            }
            break;
        case 'i':
            if (ends("iciti")) {
                r("ic");
                break;
            }
            break;
        case 'l':
            if (ends("ical")) {
                r("ic");
                break;
            }
            if (ends("ful")) {
                r("");
                break;
            }
            break;
        case 's':
            if (ends("ness")) {
                r("");
                break;
            }
            break;
        }
    }

    /* step5() takes off -ant, -ence etc., in context <c>vcvc<v>. */

    private final void step5() {
        if (k == k0)
            return; /* for Bug 1 */
        switch (b[k - 1]) {
        case 'a':
            if (ends("al"))
                break;
            return;
        case 'c':
            if (ends("ance"))
                break;
            if (ends("ence"))
                break;
            return;
        case 'e':
            if (ends("er"))
                break;
            return;
        case 'i':
            if (ends("ic"))
                break;
            return;
        case 'l':
            if (ends("able"))
                break;
            if (ends("ible"))
                break;
            return;
        case 'n':
            if (ends("ant"))
                break;
            if (ends("ement"))
                break;
            if (ends("ment"))
                break;
            /* element etc. not stripped before the m */
            if (ends("ent"))
                break;
            return;
        case 'o':
            if (ends("ion") && j >= 0 && (b[j] == 's' || b[j] == 't'))
                break;
            /* j >= 0 fixes Bug 2 */
            if (ends("ou"))
                break;
            return;
            /* takes care of -ous */
        case 's':
            if (ends("ism"))
                break;
            return;
        case 't':
            if (ends("ate"))
                break;
            if (ends("iti"))
                break;
            return;
        case 'u':
            if (ends("ous"))
                break;
            return;
        case 'v':
            if (ends("ive"))
                break;
            return;
        case 'z':
            if (ends("ize"))
                break;
            return;
        default:
            return;
        }
        if (m() > 1)
            k = j;
    }

    /* step6() removes a final -e if m() > 1. */

    private final void step6() {
        j = k;
        if (b[k] == 'e') {
            int a = m();
            if (a > 1 || a == 1 && !cvc(k - 1))
                k--;
        }
        if (b[k] == 'l' && doublec(k) && m() > 1)
            k--;
    }

    /**
     * Stem a word provided as a String. Returns the result as a String.
     */
    public String stem(String s) {
        if (stem(s.toCharArray(), s.length()))
            return toString();
        else
            return s;
    }

    /**
     * Stem a word contained in a char[]. Returns true if the stemming process
     * resulted in a word different from the input. You can retrieve the result
     * with getResultLength()/getResultBuffer() or toString().
     */
    public boolean stem(char[] word) {
        return stem(word, word.length);
    }

    /**
     * Stem a word contained in a portion of a char[] array. Returns true if the
     * stemming process resulted in a word different from the input. You can
     * retrieve the result with getResultLength()/getResultBuffer() or
     * toString().
     */
    public boolean stem(char[] wordBuffer, int offset, int wordLen) {
        reset();
        if (b.length < wordLen) {
            b = new char[ArrayUtil.oversize(wordLen, NUM_BYTES_CHAR)];
        }
        System.arraycopy(wordBuffer, offset, b, 0, wordLen);
        i = wordLen;
        return stem(0);
    }

    /**
     * Stem a word contained in a leading portion of a char[] array. Returns
     * true if the stemming process resulted in a word different from the input.
     * You can retrieve the result with getResultLength()/getResultBuffer() or
     * toString().
     */
    public boolean stem(char[] word, int wordLen) {
        return stem(word, 0, wordLen);
    }

    /**
     * Stem the word placed into the Stemmer buffer through calls to add().
     * Returns true if the stemming process resulted in a word different from
     * the input. You can retrieve the result with
     * getResultLength()/getResultBuffer() or toString().
     */
    public boolean stem() {
        return stem(0);
    }

    public boolean stem(int i0) {
        k = i - 1;
        k0 = i0;
        if (k > k0 + 1) {
            step1();
            step2();
            step3();
            step4();
            step5();
            step6();
        }
        // Also, a word is considered dirty if we lopped off letters
        // Thanks to Ifigenia Vairelles for pointing this out.
        if (i != k + 1)
            dirty = true;
        i = k + 1;
        return dirty;
    }

    /**
     * Test program for demonstrating the Stemmer. It reads a file and stems
     * each word, writing the result to standard out. Usage: Stemmer file-name
     */
    public static void main(String[] args) {
        PorterStemmer s = new PorterStemmer();

        for (int i = 0; i < args.length; i++) {
            try {
                InputStream in = new FileInputStream(args[i]);
                byte[] buffer = new byte[1024];
                int bufferLen, offset, ch;

                bufferLen = in.read(buffer);
                offset = 0;
                s.reset();

                while (true) {
                    if (offset < bufferLen)
                        ch = buffer[offset++];
                    else {
                        bufferLen = in.read(buffer);
                        offset = 0;
                        if (bufferLen < 0)
                            ch = -1;
                        else
                            ch = buffer[offset++];
                    }

                    if (Character.isLetter((char) ch)) {
                        s.add(Character.toLowerCase((char) ch));
                    } else {
                        s.stem();
                        System.out.print(s.toString());
                        s.reset();
                        if (ch < 0)
                            break;
                        else {
                            System.out.print((char) ch);
                        }
                    }
                }

                in.close();
            } catch (IOException e) {
                System.out.println("error reading " + args[i]);
            }
        }
    }

}
